Metabolic dependency of non-small cell lung cancer cells affected by three-dimensional scaffold and its stiffness

Three-dimensional (3D) extracellular matrix (ECM) microenvironment is an important regulator of the stiffness of the tumors. Cancer cells require heterogeneous metabolic phenotypes to cope with resistance in the malignant process. However, how the stiffness of the matrix affects the metabolic phenotypes of cancer cells, is lacking. In this study, the young's modulus of the synthesized collagen-chitosan scaffolds was adjusted according to the percentage ratio of collagen to chitosan. We cultured non-small cell lung cancer (NSCLC) cells in four different microenvironments (two-dimensional (2D) plates, stiffest 0.5-0.5 porous collagen-chitosan scaffolds, middle stiff 0.5-1 porous collagen-chitosan scaffolds, and softest 0.5-2 porous collagen-chitosan scaffolds) to investigate the influence of the difference of 2D and 3D cultures as well as the 3D scaffolds with different stiffnesses on the metabolic dependency of NSCLC cells. The results revealed that NSCLC cells cultured in 3D collagen-chitosan scaffolds displayed higher capacity of mitochondrial metabolism and fatty acid metabolism than that cultured in 2D culture. The metabolic response of NSCLC cells is differential for 3D scaffolds with different stiffnesses. The cells cultured in middle stiff 0.5-1 scaffolds displayed a higher potential of mitochondrial metabolism than that of stiffer 0.5-0.5 scaffolds and softer 0.5-2 scaffolds. Furthermore, NSCLC cells culture in 3D scaffolds displayed drug resistance compared with that in 2D culture which maybe via the hyperactivation of the mTOR pathway. Moreover, the cells cultured in 0.5-1 scaffolds showed higher ROS levels, which were counterbalanced by an equally high expression of antioxidant enzymes when compared to the cells grown in 2D culture, which may be regulated by the increased expression of PGC-1 alpha. Together, these results demonstrate that differences in the microenvironments of cancer cells profoundly impact their metabolic dependencies.